Gun recoil torque eliminator



Mafiih 1964 R. E. CHIABRANDY 3,

GUN RECOIL TORQUE ELIMINATOR Filed Nov. 15, 1962 United States Patent Ofi ice 3,126,791 Patented Mar. 31, 1964 3,126,791 GUN RECOIL TORQUE ELIMINATOR Robert E. Chiabrandy, Burlington, Vt., assignor, by mesne assignments, to the United States of America as represented by the Secretary of the Army Filed Nov. 15, 1962, Ser. No. 238,063 Claims. (Cl. 89-42) This invention relates to mountings for guns and more particularly to the means for mounting guns in turrets which are rotatable around the axes of elevation and azimuth.

In modern ordnance, there has been introduced for use in rotatable turrets an automatic gun in which the center of gravity is spaced from the bore line in both the elevation and azimuth planes. Considerable trouble has been experienced with the turrets in which these guns are mounted because the firing thereof frequently causes breakage of the turret drive components.

These guns are mounted so as to be accelerated rearwardly upon firing and are provided with a spring recoil adapter for absorbing the recoil forces and returning the guns to their at-rest position. An analytical study has revealed that, because the center of gravity of the guns is spaced from the bore axis thereof, the recoil forces, which act along the bore axis, are converted to torque tending to rotate the guns about the center of gravity. The turret drives attempt to restrain the rotation but the torque is so great than damage to the drives results.

It is the principal object of this invention to provide means for mounting in a turret a gun, in which the center of gravity is spaced from the bore axis, so as to eliminate the creation of torque in the turret when the gun is fired.

It is the further object of this invention to provide such mounting means which are simple in design yet are effective in eliminating firing torque.

The specific nature of the invention as well as other objects and advantages thereof will clearly appear from a description of a preferred embodiment as shown in the accompanying drawings in which:

FIG. 1 is a schematic top view of a turret with a gun mounted thereon, which gun is shown in its at-rest position;

FIG. 2 is a view similar to FIG. 1 but showing the gun in its recoil position; and

FIG. 3 is a schematic front view of the turret and gun.

Shown in the figures is a gun 12 having a receiver 14, a barrel 16 with a bore axis bb and a drum 18 mounted on one side of the receiver so that the center of gravity of the gun, noted at cg, is located away from the bore axis in both the elevation and azimuth planes.

Gun 12 is mounted in a turret 20 having an azimuth ring 22 which is rotatable around an azimuth axis a-a which passes through bore axis bb. Azimuth ring 22 is provided with vertical supports 24 for elevation bearings 26 which provide for rotation around an elevation axis e-e which also passes through bore axis bb.

A front-mount 28 is pivotally mounted on receiver 14 at the front end thereof and diametrically opposite drum 18 by means of a pin 30 the axis of which lies in a transversal plane passing through center of gravity cg. Frontmount 28 is slidingly engaged by T-slot means 32 to a front-slide 34 which is arranged so as to be parallel to bore axis bb when gun 12 is in its forward, at rest position as seen in FIG. 1. A rear-mount 36 is pivotally mounted on receiver 14 at the rear end thereof by means of a pin 38 the axis of which is parallel to the axis of pin 30. Rear-mount 36 is slidingly engaged by T-slot means 40 to a rear-slide 42 which is disposed at a predetermined angle, to be explained hereinafter, respective to front slide 34 and, therefore, respective to bore axis bb when gun 12 is in its at-rest position.

Gun 12 is biased to the at-rest position by a recoil spring adapter 44 which absorbs the recoil forces in the gun during the limited rearward displacement thereof to its recoil position and which returns the gun to its at-rest position. Recoil spring adapter 44 includes a bracket 46 pivotally mounted on receiver 14 at the rear end thereof by means of a stud 48 and a coil spring 50 disposed between the bracket and an abutment 52 in azimuth ring 22. Stud 48 and abutment 52 are located in the same plane as front-slide 34 and rear-slide 42 and so that the force of spring 50 passes through azimuth axis a-a during nearly all of the recoil displacement of gun 12 to the torque felt in rear-slide 42 by the spring force both in recoil and counterrecoil. If frictional damping of gun 12 in recoil is desirable, spring 50 may be located so that it does not act through azimuth axis a-a, thereby creating an additional load on T-slot means 40.

The analytical study made in determining the source of the gun firing torque shows that gun 12 in recoil, when the angular relationship of rear-slide 42 to bore axis bb is zero, tends to follow a path such that the rotation of the gun about azimuth axis a-a is always directly proportional to the displacement of the center of gravity cg rearward from its at-rest position. Examination of the magnitude of this rotation further discloses that the angle is always relatively small. Therefore, the free rotation of gun 12 in recoil, without creation of torque, can be provided by the use of two straight slides, at least one of which is angularly disposed respective to bore axis bb.

The angle through which gun 12 must rotate without creating torque in turret 20 is directly proportional to its recoil displacement and may be expressed as:

when the gun is in its at-rest position is determined by the formula arctan M131! where:

0 represents instantaneous angle of rotation of gun 12.

x represents instantaneous recoil displacement of gun 12 parallel to bore axis bb.

M represents total recoiling mass of gun 12.

I represents total moment of inertia of the recoiling mass, measured about the center of gravity cg, in the plane under consideration, i.e., azimuth.

d represents the distance between bore axis b-b and center of gravity cg, measured in the plane under consideration.

1 represents the distance, parallel to bore axis bb, be-

tween the axis of pin 38, and center of gravity cg.

represents the angle of rear-slide 42 relative to bore axis bb with gun 12 in battery position.

Therefore, where the characteristics of gun 12 and turret 20 are such that M=0.2 inch-slug (77.2 pounds), I 10.4 slug-inch 2 (4010 pound-inch d=3.0 inches, and f=l0.0 inches, and these known values are substituted in the formula for determining the angle of rear-slide 4-2,

=aretan =arctan (.577),=30

ispermitted to rotate during its recoil displacement without producing torque in turret 20.

It is noted in FIG. 3 that center of gravity cg is also spaced from bore axis bb in the elevation plane. The elevation torque can be similarly eliminated, as explained for the azimuth torque. Elevation and azimuth torque can both be eliminated by this invnetion if both are present but this would require that rear-slide 42 be provided with a compound angle. It is much simpler to balance gun 12 so that center of gravity cg is located in the elevation plane and eliminate the azimuth torque by the use of angularly disposed rear-slide 42 as hereinbefore explained or vice versa.

Thus, when gun 12 is fired, the recoil force, which acts along bore axis bb, causes the gun to be displaced rearwardly. As gun 12 is balanced to locate center of gravity cg in the elevation plane, there is no tendency for the gun to rotate in that plane. But there is a tendency for gun 12 to rotate around center of gravity cg in the azimuth plane. Because the angular relationship of rearslide 42, respective to bore axis bb, is predetermined by the formula, noted before, the rotation is not restrained as gun 12 moves in recoil and so torque is not produced. During counterrecoil, when gun 12 is moved forwardly by force of recoil spring adapter 44, torque is also eliminated by the force of the recoil spring adapter being transferred to the gun parallel to rear-slide 42 and so as to pass through azimuth axis aa.

From the foregoing it is clearly apparent that there is provided herein a simple but effective means for mounting in a turret a gun in which the center of gravity is spaced from the gun bore axis so as to eliminate torque in the turret during the firing of the gun.

Although a particular embodiment of the invention has been described in detail herein, it is evident that many variations may be devised within the spirit and scope thereof and the following claims are intended to include such variations.

I claim:

1. In combination, a gun having a center of gravity and a bore line, a turret rotatable in an elevation and an azimuth plane, and means for mounting said gun in said turret for recoil reciprocation relative thereto between an at-rest and a recoil position and so that torque is not produced in said turret by discharge of said gun when the center of gravity thereof is located away from the bore line in either the elevation or the azimuth plane of said turret.

2. The combination as defined in claim 1 wherein said mounting means includes a pair of straight slides located in the plane in which the center of gravity is located away from the bore axis, at least one of said slides being so angularly disposed relative to the bore axis when said gun is in the at-rest position that said gun rotates without restriction in the plane in which the center of gravity is located away from the bore line during recoil displacement.

3. The combination as defined in claim 1 wherein said mounting means includes a straight front slide'disposed parallel-to the bore slide when said gun is in the at-rest position, a straight rear-slide disposed at a predetermined angle respective to said front slide, said front slide, said rear slide and said bore line' being located in the plane in which the center of gravity is located away from the bore line, said predetermined angle being determined by the formula Mdf where represents the angle of said rear-slide relative to the bore axis with said gun in the at-rest position, M represents total recoiling mass of said gun, d represents the distance between the bore axis and the center of gravity measured in the plane in which said'center line is located away from the bore axis, 1 represents the distance parallel to the bore axis between the axis of said second pin, and the center of gravity, and I represents total moment of inertia of the recoiling mass, measured about the center of gravity in the plane in which the center of gravity is located away from the bore line.

4. The-combination as defined in claim 3 and including spring means disposed between said gun and said turret to absorb the recoil energy in said gun and return said gun to the at-rest position, said spring means being arranged to exert a force against said gun parallel to said rear slide.

5. The combination as defined in claim 3 wherein said gun is provided with a receiver, and said mounting means include a front mount pivotally mounted on the front end of said receiver by means of a first pin, cooperating T-slot means on said front mount and said front slide to provide sliding displacement of said front mount therealong, a rear-mount pivotally mounted on the rear end of said receiver by means of a second pin, and cooperating T-slot means on said rear mount and said rear slide to provide sliding displacement of said rear mount therealong;

arctan References Cited in the file of this patent UNITED STATES PATENTS 1,598,004 Paulus Aug. 31, 1926 

1. IN COMBINATION, A GUN HAVING A CENTER OF GRAVITY AND A BORE LINE, A TURRET ROTATABLE IN AN ELEVATION AND AN AZIMUTH PLANE, AND MEANS FOR MOUNTING SAID GUN IN SAID TURRET FOR RECOIL RECIPROCATION RELATIVE THERETO BETWEEN AN AT-REST AND A RECOIL POSITION AND SO THAT TORQUE IS NOT PRODUCED IN SAID TURRET BY DISCHARGE OF SAID GUN WHEN THE CENTER OF GRAVITY THEREOF IS LOCATED AWAY FROM THE BORE LINE IN EITHER THE ELEVATION OR THE AZIMUTH PLANE OF SAID TURRET. 